1. Field of the Invention
The present invention relates to a band blade automatic working device for automatically performing predetermined bending and cutting works a Thomson blade for pressingly cutting a paper, a plastic sheet and leather or the like and a straight shape band blade such as pressing horizontal rule for folding a paper box or the like.
2. Description of the Prior Art
As a band blade automatic working device, a technique for bending the band blade at a desirable radius of curvature and bending angle, and cutting the band blade in a predetermined measure by a computer control has already been used in practice.
Thus, the worked band blade is embedded in a groove formed on a substrate to make a sheet of pushing cutter die. The groove has a structure to be pierced from an upper surface of the substrate to a bottom surface thereof. In case of forming the grooves on the substrate successively, the substrate is separated. As a means for avoiding it, in order to prevent the grooves from being continuous, the substrate has conventionally been appropriately provided with discontinuous portions of the groove, and at each position corresponding to the discontinuous portions, a back portion 51 of a band blade 50 is provided with a concave portion or a bridge 16 as shown in FIG. 5. However, in working the bridge 16, a series of manual operations are performed as below: visually recognizing the discontinuous portions of the substrate, marking the band blade 50, forming the bridge 16 based on marks, thereby having a defect wherein the operation efficiency is low.
Moreover, the band blade 50 is provided with a notch or a connection 17 formed on a blade edge 52 thereof except the blade edge 52 and a portion adjacent to the blade edge 52 corresponding to the bridge 16. In case that, as soon as completing a step for pressingly cutting a development view of a paper container, a corrugated fibreboard container or the like, punched useful portions and unnecessary portions, i.e., portions adjacent to the punched useful portions are separated, it is difficult to treat them and the steps thereafter is more complicated. Therefore, the connection 17 has an arrangement wherein the connecting part is formed in order to carry a connected sheet as one body until reaching a missing leaf step. Then, the connection 17 is usually formed by a grinding work. A size of the connection 17 is different according to each punched paper thickness. For example, a connecting work has a width of about 1 mm, a depth of about 1 mm and more than 4 connections are usually arranged on a pair of punching dies. The connection 17 is formed in a final step wherein the bridge 16 cannot be visually recognized after embedding the band blade 50 in the groove of the substrate. As a result, working the connection 17 is performed at the blade edge or the portion adjacent to the blade edge, thereby causing an inconvenience to overlap the bridge 16. However, the portions forming the connection 17 requires not to overlap the bridge 16 so as to maintain a strength of the band blade 50. Therefore, in working the connection 17, the substrate where the worked band blade is embedded is marked so as to indicate the "connecting" position, whereby a blade edge has conventionally been formed by a grinding work based on marks.
As mentioned above, the operation for forming the bridge 16 and the connection 17 is still performed visually with the result that there are defects wherein the measuring accuracy is low and the operation efficiency is bad.